1. Field of Technology
The present invention generally relates to a microfilm duplicating apparatus and, more particulaily, to the microfilm duplicating apparatus for duplication microimages, photographically recorded on a photographic film, onto an unrecorded photographic film.
2. Description of the Prior Art
From, for example, the Japanese Laid-open Patent Publication No. 58-149572 and the U.S. Pat. No. 4,561,769, an electrophotographic microfilming apparatus is well know, the microfilming apparatus disclosed therein makes use of, as shown in FIGS. 10 and 11 of the accompanying drawings, a 2-reel cassette 12 having a length of recording medium (hereinafter referred to as a "recording strip") M accommodated within the cassette 12 with its opposite ends secured to respective reels 13. The recording strip M is comprised of a length of electrophotographic film 14 and a length of magnetic recording tape 15 jointed lengthwise with the length of the electrophotographic film 14, or the film section of the recording strip M, is used to record, on reduced scale, by means of an electrophotographic recording process, a plurality of images of documents desired to be stored, while the length of the magnetic recording tape 15, or the magnetic tape section of the recording strip M, is used to record, by means of a magnetic recording process, retrieval data descriptive of the contents of the respective images of the documents so recorded on the film section 14.
While the microfilming apparatus of the type referred to above and utilizing the 2-reel microfilm cassette is satisfactory, office documentation at different sections or departments of an establishment such as an office, a company or an institute would be expedited if identical recordings of the particular documents are readily available at the respective sections or departments. If only one recording of the documents is available in the establishment, it will often happen that an office clerk belonging to a particular section or department has to resort to the different section or department where the recording is kept.
If recording of documents is made on a photographic material such as, for example, a microfiche or a roll of film utilizing silver halide materials, the identical recordings of the documents can be relatively quickly and efficiently prepared by the use of a well-known contact printing technique wherein an unexposed photographic recording medium is held in contact with the photographic master recording at the time of exposure to the luminous flux and is, thereafter, developed and fixed to produce images identical with those born in the master recording.
However, when it comes to the electrophotograhically recorded microfilm, any technique similar to the photographic contact printing technique cannot be employed in making duplications of the electrophotographically recorded microfilm because the electrophotographic recording system requires a process of electrostatic charging, exposure, development and fixing all sequentially subjected to the electrophotographic recording medium.
In view of the foregoing, when documents are to be recorded or duplicated on the encased electrophotographic recording medium, that is, the electrophotographic recording medium contained in the 2-reel cassette such as shown in and described with reference to FIGS. 10 and 11, the number of the microfilm cassettes required has to be determined before the documents are actually recorded, or very time-consuming and complicated procedures are required at the time the necessity arises for one or more extra microfilm cassettes having the identical recordings of the particular documents. Should one one more extra microfilm cassettes be needed, for example, for distribution to the different sections or departments of the establishment, and if the necessity has arisen after one microfilm cassette had been prepared, those jobs which have been executed for the preparation of such one microfilm cassette have to be repeated.
Accordingly, in a microfilm duplication system wherein no contact printing technique can be employed, each of the images recorded on the master microfilm must be optically reproduced at equal magnification and then projected onto the unexposed microfilm for duplicate purpose.
Thus, where the optical system is used, numerous requirements not hitherto encountered have to be satisfied in view of the fact that each frame of the microfilm which bears the respective image to be duplicated is very minute. Such requirements include that the minute image must be reproduced at 1:1 magnification, a high resolution must be attained, and the optical system must be so designed as to cope with various limitations imposed bv the microfilm cassette, where duplication is desired to be made with the use of the previously discussed electrophotographic microfilms encased in the respective cassettes, because of the relationship with the processing head operable to execute an electrophotographic process from the electrostatic charging to the fixing, particularly the relationship with the electrophotographic development, and also because of the presence of limitations resulting from the position of the cassette specified to achieve a stabilized movement of the microfilm.